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Texas Instruments LM3450AMTX/NOPB
- Part No.:
- LM3450AMTX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3450AMTX/NOPB.pdf
- Description:
- IC LED DRVR OFFL ANALOG 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,791
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Product details
Overview
LM3450AMTX/NOPB from Texas Instruments is a dimmable LED driver IC with integrated active power factor correction (PFC) and phase-dimming decoder, operating in critical conduction mode (CRM), delivering 70:1 PWM dimming output at 500 Hz, supporting 10–100W isolated flyback LED loads, and featuring dynamic hold current for triac dimmer compatibility.
For engineers reviewing the LM3450AMTX/NOPB datasheet, LM3450AMTX/NOPB pinout, LM3450AMTX/NOPB application, or LM3450AMTX/NOPB equivalent, key selection criteria include CRM PFC regulation accuracy (±3% VFB reference), 500 Hz decoded PWM frequency tolerance (±180–700 Hz), dynamic hold circuit operation (continuous in LM3450A vs sampled in LM3450), and thermal shutdown threshold (160°C).
Technical Context
The LM3450AMTX/NOPB implements dual-loop control: a fast current-shaping loop using zero-crossing detection (ZCD) and multiplier-based peak current sensing (VAC × VCMP−VTHM), and a slow voltage regulation loop via FB error amplifier (2.50 V ±30 mV reference). It supports both isolated flyback and non-isolated boost topologies.
Its phase-dimming decoder samples rectified AC line angle, applies dynamic filtering and variable sampling rate, then remaps to a 500 Hz triangle-wave PWM output on DIM pin. The dynamic hold circuit operates continuously in LM3450A (vs sampled in LM3450), ensuring stable triac firing across 120/230 VAC systems above 15/25 W output power.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VFB Reference | 2.50 V ±30 mV - sets regulated output voltage via resistor divider; enables OVP shutdown at 1.22×VFB |
| fDIM Output Frequency | 180–700 Hz - actual decoded PWM frequency varies with input dimmer angle and VADJ setting |
| Dynamic Hold Mode | Continuous operation - ensures triac stays latched during full AC half-cycle, eliminating misfire in high-power 2-stage designs |
| Junction Temp Range | −40°C to +125°C - defines operating envelope for thermal design; θJA = 38.0°C/W (TSSOP-16) |
| VCC Operating Range | 8.5 V to 20 V - powers internal bias rails; UVLO rising threshold = 13.0 V, falling = 7.9 V |
| CS Current Limit | 1.50 V threshold - triggers immediate GATE turn-off when sense resistor voltage exceeds limit, protecting MOSFET |
| ZCD Input Threshold | 1.50 V ±50 mV - detects transformer demagnetization zero-crossing to terminate off-time in CRM flyback |
Pinout & Package
LM3450AMTX/NOPB is housed in a 16-pin TSSOP package (Package Number PW), thermally enhanced for surface-mount assembly in compact LED driver PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF | 3 V reference output | Stable 3.0 V ±0.15 V source for external biasing or VADJ divider; max 3 mA load |
| VADJ | Analog adjust input | Sets dimming range: connected to VREF for 70% range, to GND for low-power mode (75 mV threshold) |
| FLT2 | Second filter pole input | Connects RC network to refine phase-dimming angle filtering; complements FLT1 for smooth transitions |
| FLT1 | First filter pole input | RC network input for primary dimmer angle filtering; establishes timing for PWM remapping |
| DIM | Open-drain PWM output | 500 Hz triangle waveform output; drives optocoupler or second-stage LED driver dim input directly |
| VAC | Rectified AC line sample | Accepts resistor-divided AC input (0–5.5 V); used by multiplier and angle decoder for real-time line tracking |
| COMP | Error amplifier output | Drives multiplier input; compensation capacitor to GND sets loop stability; pre-biased at startup |
| FB | Inverting feedback input | 2.50 V reference point; connects to output divider in non-isolated designs; tied to GND via 5.11 kΩ in isolated flyback |
| ISEN | Input current sense | Monitors diode bridge return path; enables dynamic hold current injection when input current drops below 200 mV threshold |
| GND | Power ground | Common reference for all analog and digital circuits; must be low-impedance plane for noise immunity |
| CS | MOSFET current sense | Connects to source of PFC switch; compares against multiplier output to regulate peak current per cycle |
| GATE | High-current gate driver | ±1.5 A peak drive; 10.5–11.5 V high-level output; 2–8 Ω pull-down resistance for fast turn-off |
| VCC | Bias supply input | 8.5–20 V input; requires 0.1 µF ceramic bypass to GND; quiescent current = 1.6 mA (no switching) |
| ZCD | Zero-crossing detector | 1.50 V threshold input; senses transformer/inductor demagnetization to trigger next on-time in CRM |
| HOLD | Dynamic hold output | Open-drain output driving external pass-FET; continuous hold current prevents triac misfire in LM3450A |
| BIAS | Pre-regulator gate bias | Drives gate of startup pass-FET; high-level = 21 V @ 100 µA, low-level = 14 V @ 100 µA |
Key Features
| Feature | Design Value |
|---|---|
| Critical Conduction Mode PFC | Enables >0.95 power factor with ZCD-triggered off-time termination and feed-forward current shaping |
| 70:1 Phase-Dimming Decoding | Maps triac firing angle to 500 Hz PWM duty cycle with programmable range via VADJ resistor divider |
| Continuous Dynamic Hold | LM3450A-specific feature: maintains triac latching current throughout entire AC half-cycle, eliminating misfire in 230 VAC >25 W designs |
| Isolated Flyback Support | FB pin disables internal error amplifier when pulled to GND via 5.11 kΩ, enabling secondary-side regulation via optocoupler |
| Over-Voltage Protection | Shuts down GATE when FB rises to 1.22×VFB (≈3.05 V); includes hysteresis to prevent chatter during transients |
Applications
| Dimmable Indoor Downlights | Outdoor Area Lighting |
|---|---|
Use Scenario: 24–48 V, 30–60 W troffer-style luminaires installed in office ceilings with standard wall-mounted triac dimmers. IC Role / Device Role / Timing Role: LM3450AMTX/NOPB serves as primary-stage PFC controller and phase-dimming decoder, generating isolated 500 Hz PWM signal sent to secondary LED driver stage. Use Value: Enables seamless 1–100% dimming without flicker or pop-on, while maintaining >0.95 PF and meeting IEC 61000-3-2 Class C harmonic limits. | Use Scenario: 100–200 W streetlight fixtures powered from 230 VAC mains, requiring robust dimming over temperature and line-voltage variation. IC Role / Device Role / Timing Role: LM3450AMTX/NOPB provides continuous dynamic hold current and CRM PFC regulation, ensuring triac compatibility across −40°C to +85°C ambient. Use Value: Eliminates dimmer-induced lamp dropout during cold starts and sustains stable dimming down to 1% output, even with aging dimmers. |
| Large-Form-Factor LED Bulbs | Commercial Troffer Retrofit Kits |
Use Scenario: A19/E26 screw-base retrofit bulbs replacing 75–100 W incandescent, operating directly from 120 VAC with integrated heat sink. IC Role / Device Role / Timing Role: LM3450AMTX/NOPB implements single-stage CRM flyback with active PFC and direct phase-dimming decoding, driving LEDs without secondary controller. Use Value: Achieves >90 lm/W efficacy with <10% THD and full-range dimming, satisfying Energy Star V2.1 and California Title 24 requirements. | Use Scenario: 2×4 ft LED troffer retrofits installed into existing fluorescent fixtures, reusing ballast bypass wiring and requiring no new wall controls. IC Role / Device Role / Timing Role: LM3450AMTX/NOPB acts as universal PFC + dimming interface, accepting legacy triac dimmer signals and delivering clean 500 Hz PWM to constant-current LED modules. Use Value: Reduces BOM count by integrating PFC and dimming decode, cutting bill-of-materials cost by 18% versus discrete controller + decoder solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver with PFC and phase-dimming decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3450MTX/NOPB | Sampled dynamic hold (not continuous); 2.50 V FB reference identical; same pinout and package | Suitable for 120 VAC <15 W or 230 VAC <25 W 2-stage designs where hold current duty cycle can be minimized | Select LM3450MTX/NOPB only when thermal budget allows intermittent hold current and output power remains below threshold limits. |
| NCP1607DR2G | No integrated phase-dimming decoder; standalone CRM PFC controller; requires external microcontroller or analog circuit for dimming decode | Used in non-dimmable or DALI/0–10 V dimmable LED drivers; lacks native triac support | Choose NCP1607DR2G when designing for non-phase-dimming interfaces or when system-level dimming logic resides elsewhere. |
Compared with LM3450MTX/NOPB, LM3450AMTX/NOPB delivers guaranteed triac stability at higher power levels due to continuous hold current, while NCP1607DR2G offers greater flexibility in non-triac systems but adds design complexity and component count for dimming functionality.
Availability
LM3450AMTX/NOPB is available at Aetrix Electronics and suitable for dimmable LED lighting, commercial troffer retrofits, and outdoor area lighting requiring stable component supply, long-term lifecycle management, and consistent parametric performance across production batches.
Supply support for LM3450AMTX/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and consumer applications.
The LM3450A product line was designed specifically for cost-effective, single-chip dimmable LED drivers with integrated active PFC and triac-dimming compatibility, targeting 10–100 W SSL applications where space, BOM count, and EMI compliance are critical.
FAQ
What is the key functional difference between LM3450AMTX/NOPB and LM3450MTX/NOPB?
The LM3450AMTX/NOPB implements continuous dynamic hold current to ensure triac dimmer stability across full AC half-cycles, whereas LM3450MTX/NOPB samples hold current only during decoding intervals. This makes LM3450AMTX/NOPB mandatory for 230 VAC >25 W or 120 VAC >15 W designs, as specified in TI's application guidance. Both share identical pinout, FB reference, and PWM decoding architecture.
Does LM3450AMTX/NOPB support isolated flyback topologies?
Yes, LM3450AMTX/NOPB supports isolated flyback designs by disabling its internal error amplifier: connect FB to GND via a 5.11 kΩ resistor, which engages an internal 5 kΩ pull-up at COMP. COMP then interfaces directly with an optocoupler's phototransistor collector, enabling secondary-side voltage regulation. The device retains full PFC and dimming decode functionality in this configuration.
What is the actual PWM frequency range delivered by the DIM pin of LM3450AMTX/NOPB?
The DIM pin of LM3450AMTX/NOPB outputs a triangle-wave PWM signal with frequency ranging from 180 Hz to 700 Hz, centered nominally at 500 Hz. This variation occurs due to internal oscillator tolerance and is confirmed in the Electrical Characteristics table (fDIM parameter). The duty cycle-not frequency-is remapped from triac firing angle, enabling precise dimming control independent of line frequency.
How does the dynamic hold circuit in LM3450AMTX/NOPB prevent triac misfire?
The LM3450AMTX/NOPB's dynamic hold circuit continuously sources current through the HOLD pin to an external pass-FET, injecting additional holding current into the triac's gate path during the entire AC half-cycle. This ensures the triac remains latched beyond its natural commutation point, preventing premature turn-off-especially critical with high-impedance or aging dimmers in 230 VAC systems above 25 W output power.
Can LM3450AMTX/NOPB operate without optical isolation in a non-isolated boost configuration?
Yes, LM3450AMTX/NOPB operates in non-isolated boost configurations by connecting the FB pin to the output voltage via a resistor divider, closing the voltage loop with its internal 2.50 V error amplifier. In this mode, COMP drives the multiplier directly, and the DIM output remains fully functional for downstream dimming control. No optocoupler is required, simplifying layout and reducing cost for Class II low-voltage LED systems.
LM3450AMTX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- AC DC Offline Switcher
- Topology:
- Flyback, Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 8.5V
- Voltage - Supply (Max):
- 20V
- Voltage - Output:
- 11.5V
- Current - Output / Channel:
- -
- Frequency:
- -
- Dimming:
- Analog
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM3450AMTX/NOPB FAQ
1.How can I place an order for LM3450AMTX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3450AMTX/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM3450AMTX/NOPB reliable?
The price and inventory of LM3450AMTX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3450AMTX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3450AMTX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3450AMTX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3450AMTX/NOPB?
LM3450AMTX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3450AMTX/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM3450AMTX/NOPB?
For technical support, including LM3450AMTX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3450AMTX/NOPB requirements.
6.How does Aetrix verify that LM3450AMTX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3450AMTX/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM3450AMTX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3450AMTX/NOPB?
All LM3450AMTX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3450AMTX/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM3450AMTX/NOPB part is unused and in its original packaging.
Return procedure for LM3450AMTX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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